Comprehending the corrosion mechanism of magnesium is of major interest in diverse fields. Typically, hydrogen evolution reaction is considered as the only cathodic reaction during Mg corrosion. However, recent works demonstrate importance of considering oxygen reduction reaction (ORR) as a second cathodic process at specific conditions. With oxygen micro-optode, we show that ORR rate was higher on slower corroding ultra-high-purity Mg (UHP-Mg), while lower on faster corroding commercially pure Mg (CP-Mg), where massive hydroxide layer impeded oxygen permeation. These findings shed light on yet another facet of complex mechanism of Mg corrosion.

理解镁的腐蚀机理是各个领域的主要兴趣。通常，析氢反应被认为是镁腐蚀过程中唯一的阴极反应。然而，最近的工作表明在特定条件下考虑将氧还原反应（ORR）作为第二个阴极工艺的重要性。使用氧气微光电二极管，我们显示在腐蚀较慢的超高纯镁（UHP-Mg）时，ORR速率较高，而在腐蚀速度较快的商业纯Mg（CP-Mg）时，ORR速率较高，后者的大量氢氧化物层阻碍了氧气渗透。这些发现为镁腐蚀的复杂机理提供了另一个方面。